Author Topic: Siemens Brothers No. 310  (Read 93 times)

Offline kuschi

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Siemens Brothers No. 310
« on: December 31, 2017, 02:52:00 PM »
I picked up on eBay a Siemens Brothers No. 310  the other day. During the disassembly of the phone, I noticed an addition to the phone which is not documented on the wiring diagram. It is some kind of a switch. It is connected to the terminals 4 and 5.

Does anyone now the function of this switch? Is to manually adjusted the speech circuit to the length of the line?